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Fix coding-related core dumps with gcc -ftrapv.

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The code was computing A - B, where A and B are pointers, and B is
random garbage.  This can lead to core dumps on platforms that
have special pointer registers, and it also leads to core dumps on
x86-64 when compiled with gcc -ftrapv.  The fix is to compute
A - B only when B is initialized properly.
* coding.c (coding_set_source, coding_set_destination): Return void.
(coding_change_source, coding_change_destinations): New functions,
with the old behaviors of coding_set_source and coding_set_destination.
All callers that need an offset changed to use these new functions.
This commit is contained in:
Paul Eggert 2012-05-26 15:27:21 -07:00
parent 38264cc938
commit c1892f1145
2 changed files with 48 additions and 17 deletions
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52
src/coding.c
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@ -847,8 +847,10 @@ static int encode_coding_ccl (struct coding_system *);
static void decode_coding_raw_text (struct coding_system *);
static int encode_coding_raw_text (struct coding_system *);
static ptrdiff_t coding_set_source (struct coding_system *);
static ptrdiff_t coding_set_destination (struct coding_system *);
static void coding_set_source (struct coding_system *);
static ptrdiff_t coding_change_source (struct coding_system *);
static void coding_set_destination (struct coding_system *);
static ptrdiff_t coding_change_destination (struct coding_system *);
static void coding_alloc_by_realloc (struct coding_system *, ptrdiff_t);
static void coding_alloc_by_making_gap (struct coding_system *,
ptrdiff_t, ptrdiff_t);
@ -927,7 +929,7 @@ record_conversion_result (struct coding_system *coding,
charset_map_loaded = 0; \
c = DECODE_CHAR (charset, code); \
if (charset_map_loaded \
&& (offset = coding_set_source (coding))) \
&& (offset = coding_change_source (coding))) \
{ \
src += offset; \
src_base += offset; \
@ -942,7 +944,7 @@ record_conversion_result (struct coding_system *coding,
charset_map_loaded = 0; \
code = ENCODE_CHAR (charset, c); \
if (charset_map_loaded \
&& (offset = coding_set_destination (coding))) \
&& (offset = coding_change_destination (coding))) \
{ \
dst += offset; \
dst_end += offset; \
@ -956,7 +958,7 @@ record_conversion_result (struct coding_system *coding,
charset_map_loaded = 0; \
charset = char_charset (c, charset_list, code_return); \
if (charset_map_loaded \
&& (offset = coding_set_destination (coding))) \
&& (offset = coding_change_destination (coding))) \
{ \
dst += offset; \
dst_end += offset; \
@ -970,7 +972,7 @@ record_conversion_result (struct coding_system *coding,
charset_map_loaded = 0; \
result = CHAR_CHARSET_P (c, charset); \
if (charset_map_loaded \
&& (offset = coding_set_destination (coding))) \
&& (offset = coding_change_destination (coding))) \
{ \
dst += offset; \
dst_end += offset; \
@ -1056,14 +1058,11 @@ record_conversion_result (struct coding_system *coding,
| ((p)[-1] & 0x3F))))
/* Update coding->source from coding->src_object, and return how many
bytes coding->source was changed. */
/* Set coding->source from coding->src_object. */
static ptrdiff_t
static void
coding_set_source (struct coding_system *coding)
{
const unsigned char *orig = coding->source;
if (BUFFERP (coding->src_object))
{
struct buffer *buf = XBUFFER (coding->src_object);
@ -1082,18 +1081,26 @@ coding_set_source (struct coding_system *coding)
/* Otherwise, the source is C string and is never relocated
automatically. Thus we don't have to update anything. */
}
}
/* Set coding->source from coding->src_object, and return how many
bytes coding->source was changed. */
static ptrdiff_t
coding_change_source (struct coding_system *coding)
{
const unsigned char *orig = coding->source;
coding_set_source (coding);
return coding->source - orig;
}
/* Update coding->destination from coding->dst_object, and return how
many bytes coding->destination was changed. */
/* Set coding->destination from coding->dst_object. */
static ptrdiff_t
static void
coding_set_destination (struct coding_system *coding)
{
const unsigned char *orig = coding->destination;
if (BUFFERP (coding->dst_object))
{
if (BUFFERP (coding->src_object) && coding->src_pos < 0)
@ -1118,6 +1125,17 @@ coding_set_destination (struct coding_system *coding)
/* Otherwise, the destination is C string and is never relocated
automatically. Thus we don't have to update anything. */
}
}
/* Set coding->destination from coding->dst_object, and return how
many bytes coding->destination was changed. */
static ptrdiff_t
coding_change_destination (struct coding_system *coding)
{
const unsigned char *orig = coding->destination;
coding_set_destination (coding);
return coding->destination - orig;
}
@ -4452,7 +4470,7 @@ encode_coding_iso_2022 (struct coding_system *coding)
nbytes = encode_designation_at_bol (coding, charbuf, charbuf_end,
desig_buf);
if (charset_map_loaded
&& (offset = coding_set_destination (coding)))
&& (offset = coding_change_destination (coding)))
{
dst += offset;
dst_end += offset;